This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A235616 #13 Nov 01 2023 23:21:04 %S A235616 2,3,7,19,37,79,127,229,307,487,523,547,727,733,757,1297,1423,1549, %T A235616 1567,1627,1747,1777,2647,2683,2713,2857,2887,3067,3361,3889,3943, %U A235616 4003,4153,4441,4651,4663,7789,7867,8209,8263,8293,8317,8443,8467,9109,9157,9343,9547,9733 %N A235616 Primes whose base-6 representation also is the base-4 representation of a prime. %C A235616 This sequence is part of the two-dimensional array of sequences based on this same idea for any two different bases b, c > 1. Sequence A235265 and A235266 are the most elementary ones in this list. Sequences A089971, A089981 and A090707 through A090721, and sequences A065720 - A065727, follow the same idea with one base equal to 10. %H A235616 Robert Price, <a href="/A235616/b235616.txt">Table of n, a(n) for n = 1..24874</a> %H A235616 M. F. Hasler, <a href="https://docs.google.com/document/d/10IM7fcAbB2tqRGuwfGvuEGUzD_IXbgXPDK0tfxN4M3o/pub">Primes whose base c expansion is also the base b expansion of a prime</a> %e A235616 E.g., 7 = 11_6 and 11_4 = 5 are both prime. %o A235616 (PARI) is(p,b=4,c=6)=vecmax(d=digits(p,c))<b&&isprime(vector(#d,i,b^(#d-i))*d~)&&isprime(p) %o A235616 (PARI) forprime(p=1,3e3,is(p,6,4)&&print1(vector(#d=digits(p,4),i,6^(#d-i))*d~,",")) \\ To produce the terms, this is more efficient than to select them using straightforwardly is(.)=is(.,4,6) %Y A235616 Cf. A235624, A235265, A235266, A152079, A235461 - A235482, A065720 - A065727, A235394, A235395, A089971 ⊂ A020449, A089981, A090707 - A091924, A235615 - A235639. See the LINK for further cross-references. %K A235616 nonn,base %O A235616 1,1 %A A235616 _M. F. Hasler_, Jan 13 2014